Fruit drop; fruit abscission

Japanese: 落果 - らっか（英語表記）fruit drop; fruit abscission

The falling of fruit from a mother tree during growth. Fruit drop can be due to physical damage, disease, insect damage, or chemical damage, or it can be physiological. Physiological fruit drop is caused by the formation of an abscission layer on the stalk, which causes cells to separate from each other. Physical fruit drop is called early fruit drop when the fruit is young, late fruit drop after the middle of development, and pre-mature fruit drop just before harvest. Early fruit drop is caused by non-fertilization, incomplete pistils, and cessation of embryo development. Late and pre-mature fruit drop is often caused by low temperatures and the nutritional state of the tree. Physiological fruit drop, which is common during the rainy season, is mainly caused by reduced photosynthesis due to cloudy weather and rainfall. Auxins (α-naphthaleneacetic acid, p- chlorophenoxyacetic acid, etc.) are used to prevent fruit drop.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

果実が生育中に母樹から落ちること。落果には物理的障害，病虫害，薬害などによるものと，生理的落果とがある。生理的落果の原因は，果柄部に離層が生じ，細胞が互いに離れる結果である。物理的落果のうち幼果時期を早期落果，発育なかば以後を後期落果，収穫直前を成熟前落果という。早期落果は不受精，めしべの不完全，胚の発育停止などによる。後期，成熟前落果は低温や木の栄養状態などによることが多い。梅雨期に多い生理的落果は曇天，降雨による光合成の低下がおもな原因。オーキシン類 (α-ナフタリン酢酸，p-クロロフェノキシ酢酸など) は落果の防止に用いられる。

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